"An initial avenue has to do with the role IRF4 could play in survival and maintenance of cells that make pigment," said Andres Ruiz-Linares, a professor at the University College London Genetics Institute who led the study.

Understanding how the gene interacts with other genes controling hair colour, for example, might yield cosmetic applications that block the fade to grey as hair grows in the follicle, he said.

Setting aside unresolved ethical issues, one could even "wildly contemplate" the use of gene editing, a ultra-precise cut-and-paste process for altering DNA sequences, he said.

But the IRF4 variant that favors grey also produces fair hair, he cautioned, so tinking with the gene could also mean fewer blondes.

In the study, published in the peer-reviewed journal Nature Communications, Ruiz-Linares and three dozen colleagues investigated the genetic triggers for facial hair, the prevalence of "mono-brows", hair colour and shape, balding and greying.

This is well-traveled ground scientifically, but the size and original design of the research yielded a trove of new results.

Another gene, PRSS53, for example, was found to influence curliness, shedding light on the evolution of hair shape that led to straight hair in East Asia and among Native Americans.

A variant of a third gene, PAX3, was strongly associated with "mono-brow", the tendency - especially among men - for eyebrows to be joined by a bridge of facial hair.

To undertake the analysis, scientists did a so-called genome-wide association scan (GWAS) of 6,630 volunteers in Brazil, Colombia, Chile, Mexico and Peru, matching similarities in their DNA with physical traits.

But rather than selecting subjects that shared a common ancestry - all northern Europeans or Japanese, for example - the researchers deliberately mixed things up.

Nearly half the participants were of European background, 40 percent were Native American, and six percent were of recent African origin.

Ever since 1890, when the use of anesthetics and antiseptics made it unlikely for people to die getting a nose job, cosmetic plastic surgery has been part of the global culture. By the 1920s, plastic surgery grew ever more common, and became associated with vanity. New techniques developed during World War II helped further increase demand for -- and types of -- the elective surgeries.

The era of minimally-invasive techniques has marked a new generation of plastic surgery options, with 14.6 million cosmetic procedures performed in the United States in 2012, up 5 percent since 2011. Here are the current most popular cosmetic surgeries, according to the American Society of Plastic Surgeons.

By the 1920s, the world of cosmetic surgery had shifted. By then, the first textbook about facial cosmetic surgery was in circulation, called "The Correction of Featural Imperfections" by Charles Miller. Women sought face lifts for reasons associated with vanity, not employment.

Everything from ivory to rubber has been used to augment breasts since the beginning of the 20th century. Nothing worked well (one of the first experimental substances, paraffin, had particularly bad results, with breasts that grew hard and lumpy and high rates of infection) until the Dow Corning Corporation developed the first silicone breast implants in 1961. Even though breast augmentation dropped 7 percent from 2011, it's still the No. 1. plastic surgery in the U.S., with 286,000 procedures in the U.S. in 2012. (It's followed by nose reshaping, eyelid surgery, liposuction, and facelifts.)

"People who have had significant weight loss are coming to grips with dealing with [their bodies]," said surgeon David Reath, a member of the American Society of Plastic Surgeons. "Whether they've lost weight through weight reduction surgery or diet and exercise, if they were overweight for a long period, the

skin hangs around, and it’s very demoralizing. They're looking for a solution."

One solution appears to be a procedure called an upper arm lift, which involves either liposuction or brachioplasty, a surgery that removes loose skin is removed from the back of the arms.

Plus, "anytime we start talking about arms the image of the buff First Lady comes into mind," Reath said.

"This is up in every age group of men," Reath said. "I think it's because there’s a growing awareness that there is a solution to something that's extra troubling to men of all ages. It can have a tremendous psychological effect on young men going through puberty."

In fact, the number of men having cosmetic procedures in general has increased so dramatically that Gilman thinks it will once again even out to match the rate of women who undergo plastic surgery.

New minimally invasive and cheaper procedures such as Botox and other injectable fillers took off when the economy took a downturn, Reath said.

"You could take less time off from work [to recover]; year after year it has continued to grow," he said.

In fact, the popularity of such procedures is growing so fast that Gilman believes there will come a point in the next 10 years or so where people will wonder why you didn't have a cosmetic procedure if you have sagging skin under your jaw or lines around your eyes.